Lead-in filament support assembly



Aug" 26, 1952 L.. c. WERNER LEAD-IN FILAMENT SUPPORT ASSEMBLY Filed Dec.16, 1950 Patented Aug. 26, l1952 LEAD-IN FILAMENT SUPPORT ASSEMBLY LeoC. Werner, Cedar Grove, N. J., assignor to Westinghouse ElectricCorporation, East Pittsburgh, Pa., a corporation of PennsylvaniaApplication December 16, 1950, Serial No. 201,183

3 Claims. (Cl. 313-272) 1 l. This invention relates to electrondischarge devices and more particularly to lead-in iilament supportassembly. l i

In electron discharge devices, and more especially those utilizingmulti-strand laments, considerable time and money `is expended in theassembly of the individual filament support rod and its cooperatingparts to the center support assembly of the` element mount. For example,in the pliotron type tube :each of the multiplelillament support rods isusuallyrst dropped through a round clearance hole in an upper spacerdisc of a center support assembly, said hole containing at its upper enda counterbored circular 4portion wherein is juxtaposed a metalliccylindrical washer insulated from said disc by a top ceramic washer andbottom -ceramic bushing. A suitable `spaced distance below said upperdisc, said rod is further dropped through a similar clearance hole in alower spacer disc of said center support assembly, said hole containinga like counterbored portion at its lower end and in said counterboredportion members as mentioned above, and then successively through aninverted openended metallic cup, vcoiled spring and a second open-endedmetalliccup. While said rod is held or blocked in this position, twosteel nuts, between which is gripped a. copper connectorstrap, arescrewed on the lower threaded end of said rod thereby squeezing togetherthe spring in the desired compression and locking the copper strap inclose electrical contact with the rod.

A further defect of-the prior art construction is evidenced during theoperation of the tube when the above mentioned parts become hot. Due tothe dierence of expansion in the materials used, the two nuts, which arelocked to the lower screw threaded end of each filament support rod,with the connector strap gripped between their adjacent surfaces, becomeloose. As a consequence` of this condition. a poor electricalconnection, as well as an undesirable audible vibratory hum frequentlyresults.V

Hence it has been found advantageous according to this invention toovercome the high cost of the tedious assembly `operation mentionedabove by cutting the aforementioned clearance hole in the lower spacerdisc with a radial slot extending through the peripheryof said disc. Theuse of this slot also permits the prefabrication of the rod and strap bya brazing operation. This is accomplished by peening an eyelet in saidstrap to receive `the end of the rod which is then brazed to the eyeletand thestrap after insertion of the rod in said slot, therebyeliminating an expensive threading operation of said rod and the use ofthe `undesirable nuts, and eliminating frequently recurring looseconnections of the strap.

In its general aspect the present invention has the objective ofovercoming the diiiiculties and defects of the prior art'fllamentsupport assembly.

Broadly, an object of the invention :is to provide a constructionwherein assembly oi filament support rod is simplified.

Another and specific object is to provide for introducing the rodlaterally into its clearance space in the lower spacer disc.

A further object is the prefabrication of the connector strap, eyeletand rod.

Another object is to provide a construction adaptable to use of brazing,rather than nut attachment, of said parts to the lower end of theiilament support rod.

Again, an object of the invention is to obtain close `electriealcontactof the strap with. said rod.

Once again, an object isto eliminate expensive threading on the filamentsupport rod.

Otherobjects of the invention will appear to those skilled in the art towhich it appertains as the description proceedsboth by direct recitationthereof, and by implicationfrom the context.

Referring to the accompanying drawing, in which like numerals ofreference indicate similar parts throughout the several views:

Fig. 1 is a front elevation of an electron discharge device embodyingthe invention;

Fig. 2 is a longitudinal section of the grid and filament mount andcenter support assembly;

Fig. 3 is a cross-sectional view on line III-III of Fig. 2; e

Fig. 4 is` a perspective view of the slotted lower spacer disc;

Fig. 5 is a detail longitudinal section of a portion ofthe centersupport assembly and filament support rod assembly; x

Fig. 6 is a detail sectional view of the support rod assembly.

In the specific embodiment of the invention illustrated in said drawing,thereference numeral l0 designates a glass or other basal mount for theelectrodes, namely anode l l, grid l2 and iila- I ments I3 of a triod'eelectron discharge device.

Whilea triode has been arbitrarily selected for illustrative purposes,theinvention is not to be understood as restricted to employment withtriodes only. The mount lis shown of a reentrant l type, the upper outermargin being sealed to the rim of the anodeV l I and the reentrant innermarf rod-like sleeve 29.

Vupper disc 353.

gin being attached to a grid-supporting flanged collar I4. Adjacent thisinner margin internal sealing is effected by a cross partition glassdish l5 that the interior of the anode and basal mount may be evacuated.

The said dish I5 is first sealed to lead-in assemblies I6, evenlyarranged in a sequential circular series and preferably as many innumber as filament legs to the lament and -coaxially to the hollow cup22 of metallic center pedestal 20. The present showing indicates sixlament legs and six of said lead-in assemblies I6.

Said lead-in assemblies I6 each consist of an outer lead I'I, a hollowopen-ended cup I8 to which the seal with said dish I5Vis made, andlead-in fixed and rigid posts I9, all suitably braced together incoaxial alignment. The inner ends of said post I9 are screw threaded andsituated in the vicinity of but spaced from said pedestal 20. Saidpedestal 23 consists of a circularplatel 2I joined coaxially, as bybrazing, to a hollow cup 22. The edge of said cup 22 of center pedestal20 is in a direction away from the electrodes and in turn is sealed to aglass tubulation 23, which passes out of the reentrant part of the basalmount Ill. An openingr 24 in the side of the hollow cup 22 of the saidpedestal 20 provides exhaust connection from the interior of theV deviceto the tubulation 23. i

Projecting inwardlyfrom the center pedestal 2li, coaxially aligned withthe electrodes is metallic center support assembly 25. Said `assembly 25is shown as having an integral lower plate 21 and stud member 23 withsaid plate bolted to said center pedestal 23. On'the top of stud 23 is acoaxial lowerspacer disc 3l, having a center hole therethrough ofthesame diameter as the insidefdiameter of hollow stud 28. Seated withinsaid stud 28 and projecting upward a considerable distance from lowerdisc 3i, is a hollow A suitable distance above lower disc 3I said sleeve29 is joined to an upper spacer disc 3G along the sidewalls of a centerhole of said upper disc 30, thereby holding upper disc 30'and lower disc3| in parallel spaced relation to each other and transverse to saidsleeve 29. Furthermore, sleeve 29 is joined to upper disc 3) and tolower discv SI, andstud 28, as by braz- `ing thus forming center supportassembly 25.

Longitudinally of and .projecting from said support assembly 25, to thervicinity of vthe closed end of the anode, is a long coaxial rod-likecenter support 32. Said support 32 is shown as having a threadedconnection with bottom plate 21.

The upper spacer disc 33 has holes 33 therethrough in correspondingnumber and same circular sequence as the lead-in posts I9 but shownsomewhat closer to the axis than said posts I9. The upper end of theholes 33 in said disc 30 have a counterbored portion 34 so as to receiveand retain in the order named ceramic bushing 35, metallic guide washer3B, and ceramic washer 31, thereby insulating guide washer 36 from saidDisplacement of said washers 36 and 31 and bushing 35 in a directiontoward the anode end is prevented by metallic washer-like securing ring33 .situated iiatwise and coaxially upon upper-spacer disc 33 andspot'welded or otherwise secured thereto. The guide washers 33 each havear center hole to admit passage of filament support rods 39therethrough. Corresponding but larger holes are provided in a circularseries in securing ring for passage of said rods 33 without -contactbetween said rods 39 and said securing ring. Y

The lower spacer disc 3|, preferably symmetrical in shape to upperspacer disc 30, has holes 4i! and radially directed slots 4I therefromto the periphery oi the disc in corresponding number and the samecircular sequence as the lead-in posts I3. Said slots 4I as shown have awidth substantially the same as the diameter oi the holes 43 in thelower spacer disc 3|, and the said holes are each in vertical alignmentwith a corresponding hole 33 of upper spacer disc 30. Thus filamentsupport rods 33 are parallel to center support y32 when positionedcoaxially through aligned holes 33 and 4I] of the upper and lower spacerdiscs `3D and 3l; said holes 40 of the lower Vspacer disc 3I have acounterbored portion 42 next the bottom of disc 3l, said counterboredportion 42 having the same diameter and depth asv thecounterboredportion 34 of the holes 33 through upper disc 30. l

The iilament support rods 39 are quite long so Y as to situate theirlower ends remote from the `filament and subject to as little of theheat from solder, to the lower ends of saidY rods, thereby formingfilament support rod assembly 45. Furthermore, above eyelet 44 oneachrod 39 is provided a spiral spring 46 under compression. That thesesprings 46 may better withstand operating temperatures it Vis preferablethat they be made of tungsten wire. As shown, each end of each spring 46is coniined by a metallic cup 4l', individual to the respective end ofthe spring 43 on which applied.

The upper surface of the top cup 4l in. each case rests against ceramicwashers 37 on rod 33 contained in counterbored portion42 of the hole4i). To prevent contact between disc 3I and cup 4l, the outside diameterof cup 4! is less than the diameter of the 4counterbored portion '42.Also on rod33and contained within said coun-terbored portion-42 abuttingthe upper surface oi washer 31 .are guide washer 36 and a ceramicbushing 35. l Y

The filament vsupport rods 39 as mentioned above are quite long andextend a considerable distance above upper spacer disc 36 and securingring `38. The upper end of each rod 33 has a foot end of a leg ofiilamentA I3 secured thereto, as by arc welding. The end portions of theseveral lament legs are spaced by a common metallic or other plate 48carried by the upper center support 32 and are disposed radially acrossthe plate 48 and longitudinallyrof the said support 32 to which they areappropriately welded or otherwise secured. VPositive and negative sidesci power supply are suitably applied to the iilaments, and accomplishedVfor instance by connecting the positive and negative supply toalternate iilament legsfthrough the lead-in posts iS, connector-straps'43 and rods 33, in whichA arrangement center vsupport 32 is,yelectrically neutral.

-let 44 is inserted through the strap 43 and then peened over againstsaid strap thereby immovably securing said eyelet to the strap. Theeyelet 44 `and strap 43 sub-assembly is then brazed suitably iiush tothe lower end of rod 39 with silver solder, thereby forming filamentsupport rod assembly 45. i

Coiled spring 46 and containing cups 41, their open ends facing eachother, ceramic washer .31, guide washer 36 and ceramic bushing 35 areintroduced, in the order named, over the top end of filament support rod39 downwardly into position on said rod to its lower end against the topsurface of eyelet 44. The upper end of each rod 39 is pushed obliquelyupward through hole 33 inclusive of its counterbored portion 34 of upperdisc 30 and toward center support 32 until said upper end reachesapproximately its assembled height above the upper spacer disc.Compressing the above mentioned parts on the lower end of rod 39sufciently, as by the fingers of a hand, so that the upper surface ofceramic bushing 35 will clear the lower edge of lower spacer disc 3|,said rod 39 is pushed laterally toward center support 32 through radialslot 4| of lower spacer disc 3| until said rod reaches its coaxialposition in hole 40. Releasing the compression on the above mentionedparts assembled on the lower end of said rod 39 and at the same timeblocking said lower end with a suitable temporary stop 49, metal orotherwise, ceramic bushing 35, guide washer 36, and ceramic washer 31are seated, in the order named, in the counterbored portion 42 of radialslot 40, thereby locking said rod 39 in a position parallel to centersupport 32. The stop 49, as shown in Fig. 5, rests on circular plate 21of center support assembly 25 and on the head of a bolt which joins saidplate and plate 2| of the center pedestal 20. An additional one each ofceramic washer 31, guide washer 36, `and ceramic bushing 35 are thenapplied over the upper end of and around said rod 39, downward into thecounterbored portion 34 of hole 33 in upper disc 30.

When the remaining filament support rods 39, five as indicated in thisshowing, are similarly assembled with their applied `parts as abovedescribed and shown in Fig. 6, they are also applied in place upon thecenter support assembly 25. Securing ring 38 is applied over the upperends of and around center support 32 and adjacent filament support rods39, onto the top surface of upper spacer disc 30 and joined thereto, asby welding. After arc welding the foot end of each leg of filament |3 tothe upper end of the corresponding filament support rods 39 anddisposing the end portion of said filament radially across common plate48 and longitudinally of center support 32, the blocking means 49 at thelower ends of said rods 39 is removed.

Thus it will be seen from the foregoing delock said strap 43 in. close`electrical contact with said rod 39, eliminating anexpensive thread onthe lower end of said rod 39, further'simplifies the filamentsupport rodassembly 45. and `eliminates the prior art defectV of., poor'electrical' connectionv and resulting hum during -the operation of thetube. j n

Although the preferredembo'diment of myinvention has been disclosed,` itwill be 'understood that modifications may be made; within and scopeofthe appended claims.

1. 'An electron discharge: device having abasal end and a hollow anoderemote from and opening toward said basal end, a filament within saidanode having a plurality of legs with foot ends therein, rods interposedbetween the foot ends of said iilament legs and said basal end and eachconnected to a leg of the filament, said rods each having at the basalend a connector and eyelet peened together and brazed to said basal endof said rod, a spacer interposed between said rods near the basal endsthereof, said spacer having holes and radial slots therein, said slotsextending from said holes to the periphery of said spacer, said holeseach having a counterbored portion on the underside, an insulatingwasher, guide washer and insulating bushing on said rod and in saidcounterbored portion, a spring on said rod and under compression betweensaid bushing and said eyelet, a second spacer interposed between saidrods near said anode ends thereof, said spacer having a hole with acounterbored portion next the upper end thereof around and of greaterdiameter than said rod, an insulating bushing, guide washer andinsulating washer in said counterbored portion and around said rod, andmeans at the end of said counterbored portion for retaining said washersand bushing therein.

2. An electron discharge device having a basal end and a hollow anoderemote from and opening toward said basal end, a filament within saidanode having a plurality of legs with foot ends therein, rods interposedbetween the foot ends of said lament legs and said basa-l end and eachconnected to a leg of the filament, said rods each having at the basalend a connector and eyelet put together and joined to said basal end ofsaid rod, a spacer interposed between said rods near the basal endsthereof, said spacer having holes and radial slots therein, said slotsextending from said holes to the periphery of said` spacer, said holeseach having a counterbored portion on the underside, an insulatingwasher, guide washer and insulating bushing on said rod and in saidcounterbored portion, a spring on said rod and under compression betweensaid bushing and said eyelet, a second spacer interposed between saidrods near said anode ends thereof, said spacer having a hole with acounterbored portion next the upper end thereof around and of greaterdiameter than said rod, an insulating bushing, guide washer andinsulating fwasher inl the `spirit .7 8 having .at the basatif'end a'conneotorand eyelet v REFERENCES CITED' put-together'andjoined tosaidbasalehd 0f Said The following references are of record in the rod,a. spacer interposed between said rods near me of this patent: theibasal ends thereof, saidspacer having means for the lateral insertionof said rods therein, a 5 UNITED STATES PATENTS second'spacer interposedVbetween said rods near Number Name I Date said anode ends thereof, saidspacer having a 2,226,680 Wheeler et a1 Deo. 31, 1940 hole with a.lcounterbored portion next the upper 2,380,502 Clark et a1. July 31,1945 end thereof around and of'greater diameter than 2,434,529 WernerJan. 13, 1948 said rod, an insulating bushing. guide Washer 10 2,546,184Garner Mar. 27, 1951 and insulating washer in said counterbored portionand around said rod, and means at the end of vsaid counterbored portionfor retaining said washers and bushing therein.

LEO C. WERNER. 15

